This invention relates to hydrodynamic thrust bearings, and more particularly, to light-weight and reliable hydrodynamic thrust bearings used in rotating machinery.
Hydrodynamic thrust bearings rely on relative rotation between a shaft, typically referred to as the thrust runner, and a bearing to generate a non-linear fluid film between the thrust runner and the bearing. The fluid film forms when the relative rotation of the shaft and bearing interacts with the fluid to create and maintain pressurized wedges of fluid between the shaft and bearing. The pressurized fluid wedge transfers thrust or axial loads from the thrust runner to the bearing, the fluid typically being air or oil.
Each hydrodynamic thrust bearing consists of a plurality of bearing foils, also referred to as top foils, and a plurality of bumper foils. In a typical arrangement, the plurality of bearing foils and bumper foils are welded to the same side of an annular plate, the assembly forming a thrust bearing. Because thrust bearings of this type are often relatively thin, the welding process can create distortions within the annular plate that inhibits fluid film formation and decreases bearing performance. Past attempts to remedy the distortion process produced thrust bearings with multiple annular plates, the bearing foils being welded to a first annular plate and the bumper foils being welded to a second annular plate. However, thrust bearings of this type have more weight and a more complex assembly process than thrust bearings without these additional anti-distortion structures.
Moreover, manufacturing processes can introduce flaws into the thrust bearing construction that reduce service life. A typical manufacturing process can involve forming bearing components with an electrical discharge machining process or EDM process. The EDM process can form burrs or a metallic crust on the machined edges of the bearing components. Left untreated, the burrs can form cracks that eventually propagate, leading to decreased service life of the thrust bearing.
Reducing weight and increasing service life of hydrodynamic thrust bearings continues to be a goal of designers and manufacturers. Therefore, a need exists to provide a light-weight, distortion-resistant design with manufacturing processes that do not hinder the service life of the hydrodynamic thrust bearing.